Call me old-fashioned, but I like to go with the SAAMI spec for starters. Now that their drawings are available online, not much sense in not downloading those that you shoot.

So the limits are a max of 1.169" and a minimum of 1.000". Since I have been reloading I have heard this rule of thumb; when in doubt, I use a minimum seating depth that is at least equal to the half the bullet diameter of the bullet for pistols and a full diameter of the bullet for rifles.
The maximum case length is .754", the minimum is .744" (-.010" as identified in the spec). The Berry's Bullet has a diameter of .356" so if there isn't any other recommendation, I would seat it in the case half of that: .178". You did not say how long the Berry bullet is but the cartridge OAL would equal bullet length minus .178" plus .754" for an estimated starting point. Next, I would make one dummy cartridge and make sure it would cycle into the chamber from slide release.
Well looky here; a quick Google search returned this sheet that Barry's publishes:
Barry's Bullets COLThe 9mm Luger 115-grain FN bullet is .500" long and they recommend a COAL of 1.060" so the bullet is seated .194". That is pretty close to my old rule of
